Mobile devices are incredibly widespread in today's society. For example, people use cellular phones, smart phones, personal digital assistants, laptop computers, pagers, tablet computers, etc. to send and receive data wirelessly from countless locations. Moreover, advancements in wireless communication technology have greatly increased the versatility of today's wireless communication devices, enabling users to perform a wide range of tasks from a single, portable device that conventionally required either multiple devices or larger, non-portable equipment.
Mobile devices can be configured for context awareness, which allows the mobile device to be able to determine a current situation surrounding a user of the mobile device. For example, a mobile device can be aware of the present location of the user, the surrounding environment of the mobile device, the present activities of the user, the people that are presently with the user, etc. Many on-board sensors can provide the raw data from which higher level contextual inferences can ultimately be made.
Event organizers or content providers often try to gather statistics on their consumers, such as viewers of a broadcast television program, listeners of a broadcast radio program, participants or spectators of events (e.g., concerts, sporting competitions, rallies, lectures, etc.). Estimating the number of these consumers is currently a difficult and expensive task. Producing accurate estimates of demographics (e.g., age, gender, race, and location) is more difficult still. A common solution adopted by television rating agencies, such as Nielsen, is to gather statistics from a small paid subset of the population using electronic meters. Other solutions involve manual annotation, for example, police crowd counting, or volunteer surveying. High costs and low accuracy aside, there are many shortcomings of such approaches. For instance, current television rating systems suffer from an inability to generate event viewership statistics outside the home environment, difficulties in determining which family member or home resident is watching or listening at a given time, and the inability to collect statistics on non-broadcast viewing or listening (e.g., internet viewing, viewing via set-top boxes, listening via streaming or stored audio).